Detectives investigating the attempted car bombing of Glasgow airport have recovered a "claim of responsibility" written by Kafeel Ahmed, who died from burns he suffered in the attack, the Guardian has learned. Ahmed, 27, suffered more than 90% burns after he drove a Jeep laden with improvised explosives into the airport terminal, in Britain's first attempted suicide car bombing.

Evidence recovered pointing to his role in June's attempted attacks in London and Glasgow includes an email message sent just before the Glasgow attempted bombing, talking of martyrdom; CCTV footage from one of the failed car bombings in London showing a man relatives say is Ahmed, running away; evidence from a computer he used, showing visits to bomb-making websites; and his mobile phone from the smouldering Jeep.

The attack on Glasgow on June 30 came a day after two car bombs failed to go off near a crowded nightclub in the West End of London. On June 30, Ahmed sent a text message to a relative just after 1.30pm which contained a link to an email and a password to access it. Two hours later the engineer, who was born in Bangalore, crashed the Jeep into the terminal. Those who have seen the email regard it as Ahmed claiming responsibility for the attempted attacks on London and the one he was about to stage in Glasgow. According to a source, Ahmed says his actions were carried out in the name of Allah. Ahmed writes that his relative would be shocked to read what he is about to tell him about his involvement in terrorism, praises God, and says he wants martyrdom.

Initial evidence points to the relative opening the email at 4.50pm on the Saturday, 90 minutes after Ahmed had rammed the airport. From the email, the source said, it was clear he was expecting to die.

The flames that engulfed the vehicle were quickly put out, allowing Ahmed's mobile to be recovered. He is believed to have used the mobile to send either the text message or the email to his relative.

A Whitehall source said it was believed that Ahmed decided to attack Glasgow after fearing police would soon hunt him down, which meant that the planning was rushed. The Guardian understands that police have CCTV images that show Ahmed apparently running away from the scene of the first London attack, and scurrying away from a car the terrorists meant to explode. Relatives shown the images are said to be nearly certain it is him.

Police have also seized his computer and found evidence it had been used to scour websites on the construction of bombs and explosives. Ahmed died at Glasgow Royal Infirmary on August 2.

A member of Ahmed's medical team said the suspect was in a coma during his entire time in hospital. "This was one of the worst cases of burns I have ever seen," he said. "It was very traumatic for everyone involved in his care. I was surprised he survived this long."

The other man in the Jeep, the Iraqi doctor Bilal Abdullah, has been charged with conspiring to set off explosions "of a nature likely to endanger life or cause serious injury". Two other people have been charged over the attacks. A Jordanian doctor, Mohammed Jamil Asha, is charged with conspiring to cause explosions. Ahmed's brother, Sabeel Ahmed, 26, is charged with withholding information that could prevent an act of terrorism.